Identification method for the dynamic motion error of the rotary axis based on circular and elliptical test piece cutting

The rotary axis is crucial for the machining accuracy of five-axis machines, and its motion accuracy is significantly influenced by the dynamic motion error. A test of circular and elliptical test piece cutting is proposed to identify and analyze the dynamic motion error of the rotary axis. The influence of the feed rate on the dynamic motion accuracy is explained. The dynamic motion error can be divided into two types, depending on its source and manifestation: dynamic error inside the servo loop (DEIS) and dynamic error outside the servo loop (DEOS). At different feed rates, elliptical test piece cutting and kinetics analyses are conducted to identify the DEIS, and circular test piece cutting together with double ball bar (DBB) tests are conducted to identify the DEOS. On-machine inspection and the coordinate measuring machine (CMM) calibration are performed. By combining the DBB test and kinetics analysis results, the DEIS and DEOS are identified and analyzed. The experimental verification shows that the DEIS and DEOS change according to the feed rate and can be determined from the machining error of the test piece. Consequently, the proposed method offers an effective reference for improving the motion accuracy of the rotary axis.